Change the build process

- [x] remove yeoman and start from the scratch
- [x] setup `grunt-contrib-coffee` (compiler for coffescripts)
- [x] migrate sources to CoffeeScript
- [x] setup `grunt-coffeelint` (kind of jslint for coffeescripts)
- [x] handle css/less styles
- [x] setup `grunt-bower-task` (provides better integration with grunt and bower, https://github.com/yatskevich/grunt-bower-task)
- [x] setup `grunt-karma` for javascript specs
- [x] add some missing js specs
- [x] setup `grunt-contrib-watch`
- [x] create `README` and document the build process